EP0108386B1 - Système d'enregistrement à pistes servo inférieures avec transducteur double - Google Patents

Système d'enregistrement à pistes servo inférieures avec transducteur double Download PDF

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Publication number
EP0108386B1
EP0108386B1 EP83110921A EP83110921A EP0108386B1 EP 0108386 B1 EP0108386 B1 EP 0108386B1 EP 83110921 A EP83110921 A EP 83110921A EP 83110921 A EP83110921 A EP 83110921A EP 0108386 B1 EP0108386 B1 EP 0108386B1
Authority
EP
European Patent Office
Prior art keywords
transducer
magnetic
transducers
layer
track
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP83110921A
Other languages
German (de)
English (en)
Other versions
EP0108386A1 (fr
Inventor
Hideo Tanaka
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NEC Corp
Original Assignee
NEC Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP19318482A external-priority patent/JPS5982623A/ja
Priority claimed from JP5182583A external-priority patent/JPS59177770A/ja
Application filed by NEC Corp filed Critical NEC Corp
Publication of EP0108386A1 publication Critical patent/EP0108386A1/fr
Application granted granted Critical
Publication of EP0108386B1 publication Critical patent/EP0108386B1/fr
Expired legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/33—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only
    • G11B5/39—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects
    • G11B5/3903—Structure or manufacture of flux-sensitive heads, i.e. for reproduction only; Combination of such heads with means for recording or erasing only using magneto-resistive devices or effects using magnetic thin film layers or their effects, the films being part of integrated structures
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
    • G11B5/3103—Structure or manufacture of integrated heads or heads mechanically assembled and electrically connected to a support or housing
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/127—Structure or manufacture of heads, e.g. inductive
    • G11B5/31—Structure or manufacture of heads, e.g. inductive using thin films
    • G11B5/3109—Details
    • G11B5/3116—Shaping of layers, poles or gaps for improving the form of the electrical signal transduced, e.g. for shielding, contour effect, equalizing, side flux fringing, cross talk reduction between heads or between heads and information tracks
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
    • G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
    • G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B5/596—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on disks
    • G11B5/59633—Servo formatting
    • G11B5/5965—Embedded servo format

Definitions

  • the present invention relates to magnetic recording systems, and more particularly to high track density recording systems employing buried servos for faithful track following operations.
  • Buried servos have been recognized as an effective means for faithful track positioning control.
  • a prior art system typically shown and described in United States Patents Nos. 4,313,140, 4,314,289 and 4,318,141 employs a single-gap transducer for recording a data signal while at the same time sensing prerecorded servo control signals.
  • the recording circuit of the system includes an AC bias and a high-pass filter to improve the signal-to-noise ratio of the servo control signals.
  • a notch filter is further required to suppress the data signal of the frequencies to reduce the counter emf.
  • US-A-3 956 769 discloses a magnetic recorder comprising a transducer head which contains two separate magnetic flux paths. This head is designed for simultaneously reading the several tracks in an inner layer and for transcribing data in an outer layer of a medium.
  • the flux path devoted to reading the several tracks comprises a core with a gap therein.
  • the other flux path devoted to transcribing data in a layer comprises a core and a data gap.
  • a servo winding is wound around a first core and a data winding is wound around a second core. Both cores may be made from any convenient ferrite material.
  • a magnetic recorder has a pair of first and second transducers arranged in the longitudinal direction of a record track.
  • the magnetic recorder is adapted to exchange signals with a magnetic record medium having a servo control signal prerecorded in a lower layer of said medium.
  • a recording circuit is connected to the first transducer for recording a data signal along the record track in an upper layer of the medium.
  • a reading circuit is connected to one of the first and second transducers for reading the recorded data signal.
  • To the second transducer is connected a servo control circuit connected for reading the prerecorded servo control signal and deriving therefrom a position error signal in response to which the position of the transducers is controlled.
  • Said read back circuit is connected to said first transducer.
  • Said second transducer is offset with respect to said first transducer in a direction away from the surface of said record medium to eliminate higher harmonics of said prerecorded control signal.
  • EP-A-0242887 European Patent Application No. 87106964.7 (EP-A-0242887) being a divisional Application originating from this Application.
  • a magnetic record medium 1 comprises a suitable substrate 2 supporting a magnetic coating 3.
  • a slider 4 having a pair of transducers 5a and 5b in the rear scans a data track 6 along the surface of coating 3.
  • the slider 4 has a relatively large bottom surface sufficient to produce an air cushion that enables it to float slightly above the surface of the record medium 1.
  • the slider 4 may be mounted on a movable arm which is driven by an actuator, not shown, in a direction perpendicular to the data tracks 6..
  • a recorder employing the present invention uses so-called buried servo or track position indicating signals.
  • positions indicating signals have already been recorded in a lower layer 3a of the coating 3 having a high retentivity by means of a transducer exclusively used for such purposes in a manner as described in the afore-mentioned U.S. Patent 4,318,141.
  • the format of the lower layer consists of alternating adjacent bands of servo tracks.
  • the first band consists of one servo frequency recorded continuously around the track and the second band consists of the other servo frequency recorded in like manner.
  • the data track 6 is defined as the point where the transducers 5a and 5b lie half over the first servo track and half over the second servo track.
  • the readback signal contains equal amounts of the two servo frequencies and the data track is centered over the boundary between these servo tracks.
  • a digital data signal is supplied from a terminal 7 through a recording amplifier 8 to the transducer 5a.
  • the amplifier 8 strengthens the signal so that the magnetic flux lines generated by the transducer 5a are confined in an upper layer 3b of the magnetic coating 3 having a lower retentivity than the lower layer 3a.
  • a readback amplifier 9 is also connected to the transducer 5a which picks up data and position control signals during readback operations. The signals amplified by readback amplifier 9 are fed to a high-pass filter 10 to eliminate the position control signals and pass the data signal to an output terminal 11.
  • a servo amplifier 12 which is coupled to a low-pass filter 13 for eliminating the data signal and passing the position control signals to a two-frequency detector 14 which detects the two servo frequencies.
  • a differential amplifier 15 compares the servo frequency signals with each other to derive a position error signal. This position error signal is applied to a head position servo 16 to maintain on-track condition during record and readback operations.
  • Transducers 5a and 5b are of identical construction, each comprising a core 20 having a magnetic gap 21 and a coil 22.
  • the core 20 comprises a first core element 20a which is in the form of a layer formed by vacuum deposition of nickel-ferrite compound and a second core element 20b likewise formed by vacuum deposition.
  • Between the core elements 20a and 20b is a section of the coil 22 which is embedded in an insulator 23.
  • the remainder of the coil 22 is embedded in a bulk of insulator 24 with which the core structure 20 is entirely covered.
  • a suitable material for the insulator 23 is AI 2 0 3 .
  • the coil structure 22 is likewise formed by a vacuum deposition technique.
  • the transducers 5a and 5b are cemented together so that their pole faces run parallel with each other in a direction transverse to the data track.
  • the length of gap 21 of each transducer i.e., the length as measured along the longitudinal direction of track 6, is chosen to operate with the frequencies of the data and position control signals to be exchanged with coating 3.
  • the transducers 5a and 5b are cemented by way of an insulative slab 26 to an insulative block 25.
  • the block 25 forms a greater part of the slider structure and has its front lower edge bevelled as shown at 27 to enable it to ride on the air cushion as it scans over the medium 1.
  • a nonmagnetic slab 30 with a thickness of 30 to 100 micrometers may be interposed between the transducers 5a and 5b, as shown at Fig. 3, to prevent the magnetic flux generated by transducer 5a during recording from interfering with the signal detected by the transducer 5b.
  • the transducer 5b is exclusively used for servo control purposes. According to the invention it is desirable that the pole face of the transducer 5b be offset upwardly with respect to the pole face of the transducer 5a as illustrated in Fig. 4. This offsetting serves to reduce the effect of higher harmonics of the servo frequencies, so that the signals detected by the transducer 5b each assume a single sinusoid.
  • the transducer 5b comprises a magnetoresistor 40 embedded in an insulative block 41.
  • the servo control circuit and recording circuits are isolated from each other, there is no need for the AC bias, notch filter and high-pass filter as required in the recording circuit of the prior art having a single-gap transducer. Furthermore, since the servo control circuit is not affected by the counter emf which would otherwise be generated as a result of the recording signal, the signal-to-noise ratio of the position error signal is significantly improved.
  • the transducers 5a and 5b are arranged in the longitudinal direction of the track, they can be advantageously assembled with a tolerance of 50 micrometers while at the same time satisfying the required tolerance of ⁇ 0.1 micrometers for positioning.
  • a further advantage of this arrangement resides in the fact that the servo control is not affected by the inherent difference in thermal expansion coefficient between the transducers and the record medium.

Claims (6)

1. Appareil d'enregistrement magnétique destiné à échanger des signaux avec un support d'enregistrement magnétique (1) le long d'une piste d'enregistrement (6), le support d'enregistrement (1) ayant un signal de servo-commande pré-enregistré dans une couche inférieure (3a) du support, comprenant:
a) une paire de premier et second transducteurs (5a, 5b) disposés dans la direction longitudinale de la piste (6);
b) un circuit d'enregistrement (8) connecté au premier transducteur (5a), afin d'enregistrer un signal de donnée le long de la piste (6) dans une couche supérieure (3b) du support (1);
c) un circuit de lecture (9, 10; 17,10) connecté à l'un des premier et second transducteurs (5a ou 5b) pour lire le signal de donnée enregistré;
d) un circuit de servo-commande (12 à 15; 17, 13 à 15) connecté au second transducteur (5b) pour lire le signal de servo-commande pré-enregistré et obtenir à partir de celui-ci un signal d'erreur de position; et
e) un moyen (16) pour commander la position des transducteurs (5a, 5b) en réponse au signal d'erreur de position, caractérisé en ce que le circuit de lecture (9, 10) est connecté au premier transducteur (5a), et en ce que le second transducteur (5b) est décalé par rapport au premier transducteur (5a) dans une direction d'éloignement de la surface du support d'enregistrement (1) afin d'éliminer les harmoniques hauts du signal de commande pré-enregistré (Figure 4).
2. Appareil d'enregistrement magnétique selon la revendication 1, dans lequel les premier et second transducteurs (5a, 5b) ont une construction identique.
3. Appareil d'enregistrement magnétique selon la revendication 1 ou la revendication 2, dans lequel le premier transducteur (5a) comprend une première couche déposée (20a) de matériau magnétique, une structure isolée de bobine (22, 23) déposée sur la première couche, et une seconde couche (20b) de matériau magnétique déposée sur la structure isolée de bobine (22, 23) afin de former un noyau magnétique (20) avec la première couche (20a), les première et seconde couches (20a et 20b respectivement) formant un entrefer magnétique (21) entre elles.
4. Appareil d'enregistrement magnétique selon l'une quelconque des revendications 1 à 3, dans lequel les premier et second transducteurs (5a, 5b) sont fixés à une coulisse (4a) ayant une surface inférieure suffisante pour créer un coussin d'air entre elle et la surface du support d'enregistrement (1).
5. Appareil d'enregistrement magnétique selon l'une quelconque des revendications 1 à 4, dans lequel le second transducteur (5b) comprend une magnétorésistance.
6. Appareil d'enregistrement magnétique selon l'une quelconque des revendications 1 à 5, dans lequel la couche inférieure (3a) du support d'enregistrement (1) a une aimantation rémanente supérieure à celle de la couche supérieure (3b).
EP83110921A 1982-11-02 1983-11-02 Système d'enregistrement à pistes servo inférieures avec transducteur double Expired EP0108386B1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP19318482A JPS5982623A (ja) 1982-11-02 1982-11-02 磁気デイスク装置のトラツク追従サ−ボ方式
JP193184/82 1982-11-02
JP5182583A JPS59177770A (ja) 1983-03-28 1983-03-28 磁気デイスク装置のトラツク追従サ−ボ方式
JP51825/83 1983-03-28

Related Child Applications (2)

Application Number Title Priority Date Filing Date
EP87106964A Division EP0242887A3 (fr) 1982-11-02 1983-11-02 Système d'enregistrement à pistes servo inférieures
EP87106964.7 Division-Into 1983-11-02

Publications (2)

Publication Number Publication Date
EP0108386A1 EP0108386A1 (fr) 1984-05-16
EP0108386B1 true EP0108386B1 (fr) 1989-02-01

Family

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Family Applications (2)

Application Number Title Priority Date Filing Date
EP83110921A Expired EP0108386B1 (fr) 1982-11-02 1983-11-02 Système d'enregistrement à pistes servo inférieures avec transducteur double
EP87106964A Withdrawn EP0242887A3 (fr) 1982-11-02 1983-11-02 Système d'enregistrement à pistes servo inférieures

Family Applications After (1)

Application Number Title Priority Date Filing Date
EP87106964A Withdrawn EP0242887A3 (fr) 1982-11-02 1983-11-02 Système d'enregistrement à pistes servo inférieures

Country Status (3)

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US (1) US4581663A (fr)
EP (2) EP0108386B1 (fr)
DE (1) DE3379127D1 (fr)

Families Citing this family (21)

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DE3714986A1 (de) * 1987-05-06 1988-11-17 Thomson Brandt Gmbh Recorder mit spurfuehrung
US5070421A (en) * 1987-09-25 1991-12-03 Fuji Xerox Co., Ltd. Magnetic disk system having tracking control using recorded information
US4962437A (en) * 1988-02-24 1990-10-09 Magnetic Peripherals Inc. Thin film servo head employing the inactive transducer coils to cancel write noise from nearby data heads
EP0330398A3 (fr) * 1988-02-24 1991-07-24 Seagate Technology International Tête de lecture magnétique
US4975791A (en) * 1988-03-22 1990-12-04 Carlisle Memory Products Group Incorporated Recording system having head transducers with controlled skew
US4979051A (en) * 1988-03-22 1990-12-18 Eggebeen James A Bimodal multi-track magnetic head
US5001579A (en) * 1988-05-27 1991-03-19 Eastman Kodak Company Method and apparatus for centering a transducer over a recorded track on a rotary storage medium
US5072322A (en) * 1988-10-17 1991-12-10 National Micronetics, Inc. Monolithic ferrite recording head with glass-protected, self-aligned, machined track
US5285331A (en) * 1989-02-23 1994-02-08 Wangtek Incorporated System for aligning a read head gap over a track of magnetic data
US5223994A (en) * 1989-10-02 1993-06-29 Behr Michael I System using superimposed, orthogonal buried servo signals
US5568331A (en) * 1989-10-27 1996-10-22 Hitachi, Ltd. Method of head positioning and magnetic recording disk drive using the same
US5461528A (en) * 1990-08-27 1995-10-24 Seagate Technology, Inc. Self bucking servo transducer
US5471354A (en) * 1990-08-27 1995-11-28 Seagate Technology, Inc. Servo head with close servo transducer placement for improved passive noise cancellation
EP0484905A3 (en) * 1990-11-09 1994-12-14 Brier Technology Interface for disk drives
US5229895A (en) * 1991-06-07 1993-07-20 Minnesota Mining And Manufacturing Company Multi-track servo recording head assembly
KR930001132A (ko) * 1991-06-07 1993-01-16 원본 미기재 다중-트랙 서보 레코딩 헤드, 녹화된 서보 트랙을 포함하는 기록 매체 및 서보 제어된 헤드 위치 결정 시스템
JPH04366411A (ja) * 1991-06-13 1992-12-18 Ngk Insulators Ltd 薄膜磁気ヘッド
US5319502A (en) * 1992-01-10 1994-06-07 International Business Machines Corporation System and method for employing buried servos within a magnetic recording medium
EP0551570A1 (fr) * 1992-01-15 1993-07-21 Wangtek, Inc. Système pour aligner une fente d'une tête de lecture sur une piste de données magnétiques
US5739974A (en) * 1993-03-09 1998-04-14 Hewlett-Packard Company System for calibrating a magnetic tape drive
US6614608B1 (en) 1999-02-22 2003-09-02 Seagate Technology Llc Buried servo patterned media

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Also Published As

Publication number Publication date
US4581663A (en) 1986-04-08
EP0242887A2 (fr) 1987-10-28
DE3379127D1 (en) 1989-03-09
EP0108386A1 (fr) 1984-05-16
EP0242887A3 (fr) 1988-01-07

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